Thermally activatable diazotype compositions



United States Patent Int. Cl. G03c 1/58 US. Cl. 96-49 17 Claims ABSTRACTOF THE DISCLOSURE Substituted s-triazinyl-thioketones and triazinylketones are couplers in thermally developable photographic elementsincorporating diazonium compounds as the lightsensitive component, whichdevelopment does not require additional alkali or alkaline releasematerials.

The scope of this invention is described by the following specificationand claims.

This invention relates to photography and in particular tolight-sensitive, thermally activatable diazotype compositions, toheat-developable photographic elements wherein such diazotypecompositions constitute the light-sensitive material, and to a thermalprocess for producing images upon such photographic elements.

It is known that diazotype compositions are useful for imagereproduction purposes, such utility being derived from the fact thatdiazo compounds (aromatic diazonium salts in particular) arelightsensitive. When exposed to light, diazo compounds are destroyed tothe extent that they can no longer form a dye by reacting with acoupling component. It is currently believed that where light energyimpinges upon a surface coated with a diazotype composition, the diazocompound reacts to form a compound having the corresponding hydroxylatedmoiety at the sight of the diazo moiety. In those areas where lightenergy is prevented from striking the surface, this diazo destructionreaction does not take place. During the development of an imagewiseexposed photographic element in which a diazotype compositionconstitutes the lightsensitive component, the unexposed diazo compoundreacts with the coupling component under alkaline conditions to form adye image which is a positive reproduction of the original.

Commercially useful photographic elements incorporating diazotypecompositions as the light-sensitive material typically requiredevelopment according to one of two well-known types of processes, themiost (or semi-dry) process and the dry process.

The moist process involves a one-component system. The light-sensitivephotographic element is prepared by coating a support material with adiazo compound and other materials such as an acidic stabilizing agent.There is no coupling component present in the coating. A photographicelement so prepared is exposed to a light source through the originalwhich is to be copied. Development is accomplished by treating theexposed element with an alkaline solution comprising a couplingcomponent and a pH adjusting agent, which development produces a dyeimage in the unexposed areas. Such developing solutions are generallycorrosive and difficult to handle.

The above mentioned dry process avoids the corrosive nature of thealkaline medium developing solution of the semi-dry process and alsoprovides a significant advantage by forming dry reproductions. Toprepare a photographic element suitable for use in the dry process, asupport material is coated with a diazo compound or compounds incombination with one or more coupling comice ponents and preferably withother known additives, such as acidic stabilizing agents. After exposureto a light source, as above described, the photographic element isdeveloped by exposing it to an alkaline atmosphere. A typically utilizedatmosphere is moist ammonia fumes. The dry process sutfers from thelimitation that noxious ammonia fumes must be adequately stored,transported and vented out of the developing machine.

In order to overcome the limitations imposed by such corrosivedeveloping solutions and noxious ammonia fumes, emphasis has been placedon processes involving thermal activation of alkali-releasing agents.Accordingly, heat activated alkali-releasing agents have been includedin the diazotype composition. Such a. composition, incorporating a heatactivated alkali-releasing agent, can be coated onto a support material.Alternately, such an alkali-releasing agent can be used independently inthe developing machine. In either case, the application of heat causesthe agent to decompose with the attendant formation of an alkalinematerial, thus triggering the coupling reaction. For example, ammoniumcarbonate, bicarbonate, acetate and formate generate ammonia whenheated. Also, ureas, thioureas, and organic amines have been suggestedwith varying degrees of success. These known alkali-releasing agents,however, tend to cause crystallization and to reduce the effectivestorage life of the photographic element incorporating a diazoniumcompound as the lightsensitive component. Moreover, continued safeguardshave been required to properly control the alkali released in thedeveloping machine.

Accordingly, it is an object of this invention to provide, forphotographic purposes, a novel, thermally activatable diazotypecomposition which does not require either a separate alkaline atmosphereor separate alkali-releasing agent for coupling.

Another object of this invention is to provide, for photographicpurposes, a new diazotype composition which couples upon the applicationof heat.

Still another object of the present invention is to provide, forphotographic purposes, a new diazotype composition which when coated ona support is' susceptible of extended storage and is transparent, freefrom haze, nontacky and non-crystalline.

An additional object of this invention is to provide a novelphotographic element which incorporates a diazotype composition in alight-sensitive layer and which photographic element is developablewithout either a separate alkaline atmosphere or a separatealkali-releasing agent.

Yet another object of the instant invention is to provide a newphotographic element which incorporates a diazotype composition in thelight-sensitive layer and which photographic element is developablesolely upon the application of heat.

Yet an additional object of the present invention is to provide a novelphotographic element which incorporates a diazotype composition as thelight-sensitive component, and which diazotype composition istransparent, free from haze, and resistant to deterioration uponstorage.

Still an additional object of the present invention is to provide a newthermal process for producing photographic images.

These and other objects of the present invention will become apparentfrom a consideration of the following specification and appended claims.

The objects of this invention are accomplished with diazotypecompositions containing a light-sensitive diazo compound and aS-Substituted s-triazine as the coupler component.

The S-Substituted s-triazines which can be employed in the practice ofthe present invention include compounds having the formula:

wherein R is a monovalent radical such as a lower alkyl radical, a loweralkoxy radical or a lower cycloalkyl radical; and Z is a divalent atomsuch as sulfur or oxygen. Typically such lower alkyl radicals have 1 to8 carbon atoms and include substituted alkyl radicals such ashydroxyalkyl radicals, for example, methyl, ethyl, npropyl, t-butyl, npentyl, n-hexyl, n-heptyl, n-octyl, hydroxyethyl, l-hydroxyoctyl, etc.Typically such lower alkoxy radicals have 1 to 8 carbon atoms such asmethoxy, ethoxy, n-propoxy, n-butoxy, n-octoxy, etc. Typically suchlower cycloalkyl radicals have 4 to 8 carbon atoms and includecyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl, withcyclohexyl being particularly useful.

Typical S-Substituted s-triazines used as couplers in the inventioninclude:

S-methyl-tetrahydro-s-triazino-2 1H) thione,

-n-propyl-tetrahydro-s-triazino-2( 1H thione,5-n-butyl-tetrahydro-s-triazino-Z( 1H thione, fi-noctyl-tetrahydro-s-triazino-Z-( 1H one,S-cyclohexyl-tetrahydro-s-triazino-2 1H thione,S-cyclohexyl-tetrahydro-s-triazino-2( 1H one,S-hydroxyethyl-tetrahydro-s-triazino-2( 1H)-thione,5-n-hydroxyoctyl-tetrahydro-s-triazino-2( 1H thione,5-n-hydroxyoctyl-tetrahydro-s-triazino-2 1H one, 5-methoxytetrahydro-s-triazino-Z( 1H thione,S-n-butoxy-tetrahydro-s-triazino-Z( 1H one,S-octoxy-tetrahydro-s-triazino-Z-( 1H one,S-n-pentoxy-tetrahydro-s-triazino-2 1H thione,

and other like derivatives within the class described.

This 5-substituted-s-triazine coupling component precludes the need foreither separate alkaline material or alkaline-release material in thedeveloping process. Although the actual mechanism is not completelyunderstood, it is believed that under the heating conditions of thedeveloping process, the saturated triazine coupling component isrearranged or reacted into a molecular structure which is alkaline incharacter. Given such a shift, however, the coupling compound is notdestroyed with respect to its coupling potential with the diazoniumsalt. Without rendering an exacting description of the kinetics of thereaction, it has been found that thermal activation of this couplingcomponent in a diazotype composition results in a clear positive imagedeveloped on the support material without added alkaline materials.

The diazotype compositions of this invention comprise any of the usualdiazo compounds (diazonium salts) suitable for producing images, whichdiazonium salts are well known in the art. They are light-sensitive andare stable at ambient temperatures and under conditions of mechanicalagitation. Suitably, they are soluble in water or other common solvents.Additionally, the diazo compound should devolop into a dye having asufliciently dark color to contrast with the background surface of thesupport.

The diazonium salts are preferably aromatic compounds having a diazomoiety attached directly to a carbon atom of the aromatic nucleus. Theremaining valence bond of the diazo moiety is filled by a suitablecation such as halogen, phosphate, nitrate, borate, oxalate, citrate,and the like. The diazonium salts can be employed to advantage as thestabilized double salts such as metal halides and non-metallicfluorides. For example, zinc chloride, cadium chloride, stannicchloride, boron trifluoride and fiuoboric acid double salts are used.Exemplary of diazonium compounds useful in diazotype compositions of theinvention are the diazonium salts resulting from diazotization of thefollowing amines:

p-amin0-N,N-dimethylaniline, p-amino-N,N-diethylaniline,p-amino-N-ethylaniline, pamino-N-ethyl-N-fl-hydroxyethylaniline,p-amino-Nmethyl-N-p-hydroxyethylaniline,p-amino-N,Ndi-,8-hydroxyethylaniline,p-amino-m-ethoxy-N-N-diethylaniline, p-arnino-N-ethyl-o-toluidine,p-amino-N-ethyl-m-toludine, p-amino-N,N-diethyl-m-toluidine,p-a-mino-N-ethyl-N-benzylaniline,p-amino-N-ethyl-N-,8-hydroxyethyl-m-toluidine,N-p-amino-phenylmorpholine, p-amino-diphenylamine,

3-aminocar-bazole,

p-amino-N-methylaniline,

p-amino-N- 8-hydroxyethyl aniline, p-amino-N- 2,6-dibromobenzyl)aniline, p-amino-N-benzyl-N-ethylaniline,p-amino-N,N-dirnethyl-3-methy1aniline,p-amino-N-cyclohexyl-2-methoxyaniline, p-aminoN,N-di fi-hydroxyethyl) 3-ethoxyaniline, p-amino-N-benzyl-Z,S-diethoxyaniline,p-amino-3-carboxy-N,N-diethylaniline,p-amino-Z-hydroxynaphthalene-4-sulfonic acid,p-arninO-N-mOrpholine-Z,S-dibutoxyaniline, and the like.

In a preferred embodiment of this invention, an acidic stabilizing agentis included in the diazotype composition to prevent premature coupling.

Acidic stabilizing agents are used to control the pH of the diazoniumsalt-coupling component admixture. Although elevated temperatures arerequired to fully activate the coupling reaction, it has been found thatsome coupling does take place after extended storage at ambienttemperatures. The acidic agent restrains such premature coupling.Examples of useful organic and inorganic acidic stabilizing agentscommonly employed for this purpose include citric acid, acetic acid,tartaric acid, oxalic acid, boric acid, succinic acid, crotonic acid,glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid,3-nitrophthalic acid, phosphoric acid, sulfamic acid, and other sulfamicacid derivatives such as cyclohexylsulfamic acid.

Other substances can be incorporated in the diazotype compositions ofthe invention, for example, background stabilizers or materials forinhibiting discoloration of the image reproductions after they are made.These include thiourea, thiocinnamine, napthalene trisulfonic acid andthe like. Other additives which can also be added are substances thatare intended to reduce the tendency of the paper to curl, such asethylene glycol, glycerol, or a polyethylene glycol; dyestutf imageintensifiers such as metal salts, including, for example, zinc chloride,ammonium sulfate, nickel sulfate, and the like; coating aids such ascolloidal silica and the like; a small amount of a wetting agent such assaponin, lauryl sulfonate, cetyl benzene sulfonate, the oleic acid amideof N-methyl taurine, and the like; and other known additives useful forknown purposes in the present art.

The components of the present diazotype compositions can be admixed witha carrier or binder material prior to coatlng on a support material.Preferably, the carrier is capable of forming a film on the supportafter drying. EX- amples of such carriers include cellulose acetate,ethyl cellulose trimellitate, cellulose acetate phthalate, ethylcellulose hexahydrophthalate, cellulose ether phthalate, celluloseacetate butyrate, cellulose butyrate, cellulose bu tyratehexahydrophthalate, ethyl cellulose, cellulose propionate and the like.The carrier is generally dissolved in .5 a volatile solvent for ease ofhandling, such as methanol, acetone, dichloromethane and otherwell-known organic solvents.

The choice of a base or support material can be widely. varied; it isusually made on the basis of the requirements to be served. Generally,paper and plastics or resins in the form of films have found wideacceptance especially where the reproduction itself is to be used as amaster. Particularly useful for work where the reproduction is to beused as a master are transparent polymeric films, such as polyethyleneterephthalate, cellulose, cellulose triacetate, cellulose acetatebutyrate, cellulose propionate, polycarbonates, polystyrenes,polysulfones, polyphenylene oxides, etc. Wood, metals, such as steel,copper, zinc, and aluminum, and ceramics, glass, and textiles are alsouseful as supports for the diazotype compositions of the invention. g

The components of the diazotype compositions, namely, the diazoniumsalt, the coupling component described, and other additives, arecombined with the carrier as by mixing the components. The admixture maybe coated onto the base in conventional manner as, for example, doctorblade, air knife, roller, or hand painting, followed by drying. It isnoted that the dried coating typically forms a transparent, continuousfilm free of crystallization.

Coating proportions of the diazotype composition can be varied inaccordance with usual practice. Useful results have been obtained in therange of between about .013.0 grams of dry diazotype composition persquare foot of coated base surface.

In use, the coated support is imagewise exposed through an originalpattern to a light source which pattern is disposed between the lightand the sensitized base. Typically, the light energy is in thewavelength range of about 3,500- 4,500 A. After exposure, the base isheated within the temperature range sufiicient to cause a dye image toappear in the unexposed areas, giving a positive reproduction of theoriginal pattern. Processing temperatures can be widely varied and arelargely dependent on the materials used. However, usual operation iswithin the range of about ZOO-400 F. The upper temperature limit isessentially fixed by the deformation and decomposition temperature ofthe support material and the coating composition present thereon.Special care should be exercised when the support material is a plasticfilm such as cellulose acetate. The lower temperature is fixed bypractical development time available, since lower temperatures reducethe activity of the coupling component.

Storage of the unexposed coated support of this invention does notsubstantially impair the quality of the image formed thereafter. In onestability evaluation, a coated cellulose acetate film was incubated for3 days at 120 F. and 35% relative humidity. After exposure to a lightsource, the incubated coating was heat developed as described above, andthe image produced was of substantially the same acceptable quality thatof the non-incubated material.

In the examples of preferred embodiments of the invention that followand elsewhere herein, proportions are expressed as parts by weightunless otherwise specifically stated.

EXAMPLE 1 A solution of 10 parts of cellulose acetate, 12 parts ofmethyl alcohol, and 56 parts of acetone is prepared. Into 25 ml. of thissolution are admixed 0.5 gram of p-diazodiethylaniline zinc chloride,0.5 gram of cyclohexylsulfamic acid, and 0.5 gram of-n-propyl-tetrahydro-s-triazino-2 (1H) thione. The admixture is coatedonto a poly (ethyleneterephthalate) film base-to a wet thickness ofabout .003 inch, or about 1.5 grams dry weight per square foot and driedat about 20 C. The dry coating is transparent, clear (free from haze),hard (free from tack), and no crystallization is observed thereon. Thedried coated film is image-wise exposed through a master to a lightsource rich in ultraviolet energy, and passed through a belt processorover a heated drum with a 10-second cycle. The drum temperature is keptat 330 F. A brown dye image of good quality is formed in the unexposedareas, giving a positive reproduction of the master.

EXAMPLE 2 The procedure of Example 1 is repeated except that the S npropyl tetrahydro s triazino 2 (1H) thione is replaced separately and inturn by 0.5 gram portions of other triazinyl compounds, namely,

5-methyl-tetrahydro-s-triazino-2 (1H) thione,S-n-propyl-tetrahydro-s-triazino-2 (1H) thione,5-nbutyl-tetrahydro-s-triazino-2 (1H) thione,S-n-octyl-tetrahydro-s-triazino-2 (1H) one,5-cyclohexyl-tetrahydro-s-triazino-2 (1H) thione,S-cyclohexyl-tetrahydro-s-triazino-2-(1H) one,S-hydroxyethyl-tetrahydro-s-triazino-2 (1H) thione,5-n-hydroxyoctyl-tetrahydro-s-triazino-Z (1H) thione,S-n-hydroxyoctyl-tetrahydro-3-triazino-2 (1H) one,5-methoxy-tetrahydro-s-triazino-2 (1H) thione,S-n-butoxy-tetrahydro-s-triazino-2 (1H) one,5-n-octoxytetrahydro-s-triazino-2 (1H) one, andS-n-pentoxy-tetrahydro-s-triazino-2-(1H) thione.

Brown dye images of the same good quality of the image of Example 1 areobtained in the unexposed areas in each instance. 1

EXAMPLE 3 In a modification of Example 1, a paper sheet is used in placeof the polyester film. A dye image of good quality is obtained in thepaper, which dye image corresponds to the unexposed image area-s.

EXAMPLE 4 An image is made as in Example 1 except that the triazinylcompound used is 5-n-butyl-tetrahydro-s-triazino-Z- (1H) thione. Thisimage-bearing film is in turn used as a master on a new second sampleprepared as in Example 1. The resulting second generation dye image hascharacteristics essentially the same as the dye image of Example 1.

Although the invention has been described in considerable detail withreference to certain preferred embodiments thereof, it will beunderstood that variations and modifications can be effected withoutdeparting from the spirit and scope of the invention as describedhereinabove and as defined in the appended claims.

We claim:

1. A thermally activatable light-sensitive diazo-type compositioncomprising:

(1) a light-sensitive diazonium salt;

(2) a coupling component having the general formula:

wherein R is a monovalent radical selected from the group consisting ofa lower alkyl radical, a lower alkoxy radical, and a lower cycloalkylradical, and Z is selected from the group consisting of a sulfur atomand an oxygen atom; and,

(3) an acidic compound employed to prevent the composition fromprecoupling.

2. A thermally activatable diazotype light-sensitive compositioncomprising:

( 1) an aromatic light-sensitive diazonium salt;

(2) a coupling component having the general formula:

wherein R is an alkyl radical having 1 to 8 carbon atoms; and, (3) anacidic compound employed to prevent the composition from precoupling. 3.A composition as described in claim 2 wherein the R substituent is ann-propyl radical.

4. A composition as described in claim 2 wherein the R substituent is ann-butyl radical.

5. A thermally activatable diazotype light-sensitive compositioncomprising:

(I) an aromatic light-sensitive diazonium salt; (2) a coupling componenthaving the general formula:

wherein R is a hydroxyalkyl radical having 1 to 8 carbon atoms; and,

(3) an acidic compound employed to prevent the composition fromprecoupling.

6. A thermally activatable diazotype light-sensitive compositioncomprising:

(1) an aromatic light-sensitive diazonium salt; (2) a coupling componenthaving the general formula:

S H C wherein R is an alkoxy radical having 1 to 8 carbon atoms; and,

(3) an acidic compound employed to prevent the composition fromprecoupling.

7. A thermally activatable diazotype light-sensitive compositioncomprising:

(1) an aromatic light-sensitive diazoniu-m salt; (2) a couplingcomponent having the general formula:

wherein R is a cycloalkyl radical having 4 to 8 carbon atoms; and,

(3) an acidic compound employed to prevent the composition fromprecoupling.

8. A thermally activatable diazotype light-sensitive compositioncomprising:

(1) an aromatic light-sensitive diazonium salt;

(2) a coupling component having the general formula:

wherein R is an alkyl radical having 1 to 8 carbon atoms; and,

(3) an acidic compound employed to prevent the composition fromprecoupling.

9. A thermally activatable diazotype light-sensitive compositioncomprising:

( 1) an aromatic light-sensitive diazonium salt; (2) a couplingcomponent having the general formula:

g HN NH H35 CH2 wherein R is a hydroxyalkyl radical having 1 to 8 carbonatoms; and,

(3) an acidic compound employed to prevent the composition fromprecoupling.

10. A thermally activatable diazotype light-sensitive compositioncomprising:

(1) an aromatic light-sensitive diazonium salt; (2) a coupling componenthaving the general formula:

wherein R is an alkoxy radical having 1 to 8 carbon atoms; and,

( 3) an acidic compound employed to prevent the composition fromprecoupling.

11. A thermally activatable diazotype light-sensitive compositioncomprising:

( 1) an aromatic light-sensitive diazoniurn salt; (2) a couplingcomponent having the general formula:

9 -cyclohexyl-tetrahydro-s-triazino-2 (1H) one,5hydroxyethyl-tetrahydro-s-triazino-2 (1H) thione,S-n-hydroxyoctyl-tetrahydro-s-triazino-2 (1H) thione,5-n-hydroxyoctyl-tetrahydro-s-triazino-Z (1H) one,S-methoxy-tetrahydro-s-triazino-Z (1H) thione,S-n-butoxy-tetrahydro-s-triazino-2 (1H) one,5-n-octoxy-tetrahydro-s-triazino-2 (1H) one, and5-npentoxy-tetrahydro-s-triazino-2 (1H) thione.

14. A thermally activata ble light-sensitive diazotype composition asdescribed in claim 1 wherein the lightsensitive diazonium salt is anaromatic compound having a diazo moiety attached directly to a carbonatom of an aromatic nucleus.

15. A photographic element comprising a support having a layer coatedthereon said layer comprising a thermally activatable light-sensitivediazotype composition as described in claim 1.

16. A photographic process for treating an imagewise exposedphotographic element comprising a support having a layer coated thereonsaid layer being a thermally activatable light-sensitive diazotypecomposition compris- (1) a light-sensitive diazonium salt;

(2) a coupling component having the general formula:

Z II 0 wherein R is a monovalent radical selected from the groupconsisting of a lower alkyl radical, a lower alkoxy radical, and a lowercycloalkyl radical, and

Z is selected from the group consisting af a sulfur atom and an oxygenatom; and,

(3) an acidic compound employed to prevent the composition fromprecoupling, said process comprising heating such photographic elementWithin the temperature range necessary to thermally activate saiddiazotype composition and thereby producing a positive visible image.

17. The process of claim 16 wherein said heating is carried out in therange of about 200 to 400 F.

References Cited UNITED STATES PATENTS 2,016,521 10/ 1935 Steindorif.2,536,398 10/1947 Slifkin 96-91 2,688,543 9/1954 Von Glahn et al. 96-91XR 2,826,500 3/1958 Keim. 3,039,872 6/1962 De Boer et al. 96-913,140,180 7/1964 Fritz 96-75 3,199,982 8/1965 Kashiwabava 96-91 XRFOREIGN PATENTS 983,665 2/ 1965 Great Britain. 1,115,496 5/ 1968 GreatBritain.

864,951 7/1949 Germany.

NORMAN G. TORCHIN, Primary Examiner C. BOWERS, Assistant Examiner U.S.Cl. X.R.

